Modern meat grinding systems not only grind meat, but also separate meat from undesirable material, such as gristle, hard fat, connective tissue, sinew, and bone. Such systems typically provide the unprocessed meat to a pump or screw system, which delivers the unprocessed meat to a knife rotating against a perforated plate. The knife cuts the meat into smaller pieces as the pump or screw forces the meat through the perforated plate. Centrifugal force generated by the pump or rotating screw drives the meat toward the edges of the plate and concentrates the undesirable material near the center of the plate. The plate typically contains an opening into a pipe that directs the undesirable material to a storage container. Once enough of the undesirable material has been collected, the undesirable material is fed through a second meat grinding system to further separate any remaining meat from the undesirable material in a reclamation process similar to that described above. The meat reclaimed from the undesirable material is then added back to the meat ground in the initial pass and the further resulting undesirable material is discarded or otherwise processed separately.
One drawback associated with such prior art devices is the delay in the second processing of the undesirable material. In the event that a batch of meat is found unfit for use, the meat is contaminated, the undesirable material may contain meat processed over several hours, allowing a single batch of bad meat to spread contamination across several lots of processed meat. Contamination can be forward looking or rearward looking. In forward looking contamination, a batch of meat is found to be unfit for use. Undesirable material collected from this batch and processed jointly with that of other batches also contaminates the batch in which it is reintroduced. In rearward looking contamination, a batch of meat containing reclaimed meat from undesirable material that is found to be unfit for use has the potential to have been contaminated not only by processing of itself, but also by that of every batch whose undesirable material was included in the rework. When contamination is detected and limited to the forward looking scenario, containment is only somewhat problematic. Containment of a contamination detected in a rearward looking scenario however is difficult to contain. In reality, many contamination scenarios occur with both forward and rearward looking scenarios simultaneously and are difficult to contain. It would therefore be desirable to provide the second processing in conjunction with the first processing so that the meat is not temporally or physically separated, thereby reducing the cross contamination between lots of meat.
Another drawback associated with such prior art devices is the delay in the secondary processing of the undesirable material. Pathogen growth is elevated at higher temperatures. As such, meat is held in coolers typically around the freezing point to suppress pathogen growth rates. Meat should be removed from the cooler only for short durations to be processed and promptly returned to the cooler as processing rooms temperatures are typically warmer (38° F.-40° F.) than the generally accepted safe fresh meat holding cooler temperature (28° F.-32° F.). When undesirable meat sits in a community vessel for an extended period of time at the elevated temperature, the risk of pathogen growth increases substantially. It would therefore be desirable to provide the second processing in conjunction with the first processing so that the total processing time and time out of the safe temperature range is minimized.
Another drawback associated with such prior art devices is that exposure to humans is a significant source of contamination. Undesirable material held in a container is exposed to additional human interaction through the coordination and transportation of the collection vessel to the second grinding operation. It would therefore be desirable to provide the second processing in conjunction with the first to eliminate all such additional exposure of the product to humans.
As shown in U.S. patent application number 2012/0286077, which is incorporated herein by reference, it is known to provide a second meat grinder with a second drive system to take the undesirable material from the first meat grinding process and further process the material to reclaim additional meat. One drawback associated with such prior art systems is the need for an additional drive system and the concomitant costs, weight, and maintenance associated therewith. Such systems also require a variable speed control motor to balance reclaimed meat product consistency (product definition) and temperature. The variable speed control motor adds an additional component of variability regarding quality of the resulting product, food safety of the product, system cost and system complexity. These systems also use that a valve in the waste tube to restrict the flow of undesirable material being expelled from the system. The valve requires adjustment by the operator to maintain proper operation of the device. It would be desirable to eliminate the need for such a valve. The waste material associated with such systems is meat containing bone. As protein (muscle tissue) has a higher market value than fat, it would be desirable to reclaim protein while using fat as the carrier for the undesirable waste material.
Another drawback associated with such systems is the difficulty in moving the undesirable material from the first grinder to the second grinder. Depending on the amount of undesirable material and the speed of the first grinder, the undesirable material may back up in the transfer pipe delivering the undesirable material from the first grinder to the second grinder. Such backing up inhibits the efficiency of both the first grinding and second grinding processes.
Another drawback associated with such prior art devices is the waste material exhaust pipe from the second grinder backing up and causing inefficiency associated with the second grind of the meat. It would therefore be desirable to provide a second stage meat grinding and reclamation system that did not require the additional cost, weight, and maintenance of a second drive system, and which eliminated the inefficiency associated with transporting the undesirable material from the first grinding system to the second grinding system, and exhausting the waste material from the second grinding system. The difficulties encountered discussed here and above are substantially eliminated by the present invention.